Headquarters Daily Report JULY 16, 1998 *************************************************************************** REPORT NEGATIVE NO INPUT ATTACHED INPUT RECEIVED RECEIVED HEADQUARTERS û REGION I û REGION II û REGION III û REGION IV û PRIORITY ATTENTION REQUIRED MORNING REPORT - HEADQUARTERS JULY 16, 1998 Licensee/Facility: Notification: MR Number: H-98-0106 Proposed Generic Communication Date: 07/16/98 Subject: IMPROPER INSTALLATION OF CHECK VALVES Discussion: At Cooper station, the licensee identified that the check valves manufactured by Anderson Greenwood, may not function properly at low pressures unless the valve flapper pivots in the horizontal plane. At Palo Verde Unit 1, the licensee identified excessive reverse flow through the Borg-Warner safety injection discharge check valves due to vertical misalignment. An information notice will be issued to alert the licenses of potential problems in check valve performance arising from improper installation or maintenance activities. Contact: Thomas Koshy, PECB (301)415-1176 E-mail: txk@nrc.gov _ HEADQUARTERS MORNING REPORT PAGE 2 JULY 16, 1998 Licensee/Facility: Notification: MR Number: H-98-0107 Proposed Generic Communication Date: 07/16/98 Subject: POTENTIAL FOR SHUTDOWN OF OPERATING EMERGENCY DIESEL GENERATOR Discussion: At River Bend station, the operating EDG shut down as a result of the failed temperature sensor for main bearing according to the design. This model of the Transamerica Delaval engines utilize the starting air at a reduced pressure to shutdown the EDG when protective signals are actuated. The shutdown is accomplished through the draining of the control air pressure. Therefore, if the control air-header pressure is not maintained, the EDG could trip out during a design bases event. During a loss of offsite power (loop) event, the air compressors for the starting air do not continue to run on safety buses, and consequently the control air for the EDG could deplete and cause EDG shutdown while performing its safety function. PECB has learned that such design could exist at several other nuclear stations and will issue an information notice to alert the licenses of potential problems in relying on control air for the continued operation of EDG during design bases events. Contact: Thomas Koshy, PECB (301)415-1176 E-maiL: txk@nrc.gov _ HEADQUARTERS MORNING REPORT PAGE 3 JULY 16, 1998 Licensee/Facility: Notification: MR Number: H-98-0108 Potential Safety Hazard Date: 07/16/98 Subject: POTENTIAL SAFETY HAZARD ON INGERSOLL-DRESSER PUMPS MODEL APKD Discussion: Ingersoll-Dresser Pump company has informed the NRC of a potential problem for APKD type pumps. The bearing holder for the pump suction end is connected to the outer portion of the suction head through a spider-looking support assembly with three or four support ribs. At Limerick Unit 1, one of these support ribs broke off in a Residual Heat Removal pump and it became lodged at the eye of the first stage impeller, passed through the pump, and partially blocked the flow at a jet pump assembly in the reactor vessel. The failure mode of this suction end appears to start with the migration of the suction head journal sleeve caused by the wear of the key that holds the sleeve in place. This wearout is from the accumulated operating time. Once the sleeve is detached from the shaft, it could strike the suction head causing breakage of the support rib. The manufacturer recommends prompt inspection whenever a change in pump performance or pump vibration is observed and further suggests periodic inspection of suction head, suction head journal sleeve, and retaining key. As an interim measure, increased vibration monitoring on the pump shaft and motor housing was recommended until an inspection could be conducted. The manufacturer has informed the customers that procured the pump as safety grade. The problem could apply to customer-dedicated safety related and non-safety related applications. The currently known use of these pumps are Condensate pumps, Core Spray pumps, and Residual Heat Removal pumps. Contact: Thomas Koshy, PECB (301)415-1176 E-mail: txk@nrc.gov _ REGION IV MORNING REPORT PAGE 4 JULY 16, 1998 Licensee/Facility: Notification: Texas Utilities Electric Co. MR Number: 4-98-0043 Comanche Peak 2 Date: 07/16/98 Glen Rose,Texas Senior Resident Inspector Dockets: 50-446 PWR/W-4-LP Subject: Unit 2 Power Reduction Discussion: On July 16, 1998, the licensee conservatively reduced Unit 2 generation from approximately 1140 MWe to 900 MWe (100 to 80 percent reactor power) because of low pressure turbine blade vibration. Low Pressure Turbine 1, Blade 19 has been experiencing increasing vibration with decreasing condenser vacuum resulting from increasing lake temperatures. On July 15, Blade 19 vibration reached a peak amplitude of 6.7 millimeters (mm). At 8.0 mm, plant operating procedures require operators to immediately reduce main turbine load. At amplitudes greater than 9.0 mm, blade service life decreases. The power reduction was conducted without any complications. During the power reduction, Blade 19 vibration increased as exepected to a maximum of 10.0 mm. After power was stabilized at 0630 on July 16, and Blade 19 vibration varied between 1.5 mm and 6.5 mm. A non-contact turbine blade vibration monitoring system was installed by the licensee during the second Unit 2 refueling outage because the Unit 2 main turbine experienced some minor main turbine blade cracking. The cracking occurred at a high stress location in the root of the turbine blade, and failure analysis attributed the cracking to high cycle fatigue. During this outage five additional blades with cracks were identified and replaced. During the third (most recent) refueling outage, the licensee performed 100 percent eddy current testing and 100 percent magnetic particle testing of all L-0 (last row) low pressure turbine blades. This testing revealed two additional blades with similar cracking. Unit 1 and 2 turbines are made by the Siemens Corporation. Regional Action: The resident inspectors are monitoring the licensee's activities and corrective actions. Contact: Joe Tapia (817)860-8243 Tony Gody (254)897-1500 _ REGION IV MORNING REPORT PAGE 5 JULY 16, 1998 Licensee/Facility: Notification: Pacific Gas & Electric Co. MR Number: 4-98-0044 Diablo Canyon 1 2 Date: 07/16/98 Avila Beach,California Senior Resident Inspector Dockets: 50-275,50-323 PWR/W-4-LP,PWR/W-4-LP Subject: Management Appointment at Diablo Canyon Discussion: On July 15, 1998, Pacific Gas and Electric Company announced the appointment of Dave Oatley to the position of Vice President and Plant Manager for the Diablo Canyon Power Plant. Mr. Oatley had previously been the Manager of Maintenance Services at Diablo Canyon. The licensee did not announce a replacement for Mr. Oatley in the maintenance organization. Regional Action: For information only. Contact: G. Johnston (925)975-0304 D. Allen (805)595-2354 _